1. Field of the Invention
The present invention relates generally to carburetors and more specifically to a vacuum accelerator assist module for carburetors, which provides extra fuel to the intake port of an internal combustion engine, when the engine is throttled.
2. Discussion of the Prior Art
Small internal combustion engines used on trimmers and the like are run with lean fuel mixtures to comply with government pollution regulations. In order for a small engine to accelerate with a lean fuel mixture, there must be some type of device to provide the added fuel to instantly achieve full throttle. The most common method of providing the extra fuel to a diaphragm butterfly type carburetor is an accelerator pump. However, accelerator pumps are very complicated and very expensive relative to the cost of a small internal combustion engine.
U.S. Pat. No. 6,481,699 to Aihara et al. discloses an acceleration device for a two-cycle engine. The Aihara et al. patent includes an acceleration device of a carburetor for a two cycle engine with a rotary valve, which controls air flow through both a scavenging passage and a separate air intake passage each extending through a carburetor body. However, the acceleration device is connected to an air reference chamber located below a metering fuel chamber. The air reference chamber is separated from the metering fuel chamber by a diaphragm.
Accordingly, there is a clearly felt need in the art for a vacuum accelerator assist module for carburetors, which works with either two cycle or four cycle internal combustion engines; does not require an extra diaphragm in a fuel meter chamber; and costs less to implement in a carburetor than of the prior art.